Anthropologist proposes
link between per capita energy use and fertility rate

By
David F. Salisbury
Published: Jan. 16, 2004

As world reserves of oil and natural gas dwindle over the coming decades – a prospect predicted by many energy experts – the rate at which the people in most societies around the world have babies is likely to drop precipitously as well.

Photo by Steve Green

Virginia Abernethy

That
is the prediction of anthropologist Virginia Abernethy, professor
emerita of psychiatry at Vanderbilt University , speaking on
Feb. 13 in the symposium “From the Ground Up: The Importance
of Soil in Sustaining Civilization” at the annual meeting of
the American Association
for the Advancement of Science
held in Seattle.

“The availability of energy has been a major factor in population
growth,” says Abernethy. “In the modern context, energy use per
capita affects economic activity. So a prolonged decline in energy
use per capita will tend to depress the economy which, in turn,
will cause a decline in the fertility rate.”

Abernethy's argument has two parts: the link between the availability
of petroleum and the economy, and the link between changes in
economic conditions and fertility rates.

Regarding
the first link, she points out that oil and gas are “unparalleled” sources
of energy. Not only does petroleum provide the fuel that powers
modern vehicles and the natural gas that people use for home
heating and cooking, but petroleum products are the source for
hundreds of industrial and agricultural products, including fertilizer,
pesticides and plastics. This means that petroleum cannot be
easily replaced by other fuels and feed stocks.

Despite the
fact that continuing low prices are encouraging Americans and
the inhabitants of other industrialized countries to consume
oil and gas at profligate rates, “numerous geologists,
physicists and computer scientists have calculated that petroleum
and liquid natural gas production will begin to plateau and then
decline within five to 10 years,” she says.

Courtesy
of
U.S. Department of Energy

Energy use per capita and per dollar of the Gross National Product

Such a downturn will have major economic effects, Abernethy
expects. In the United States since World War II, rising oil
prices have preceded most U.S. recessions and unemployment
rates have risen following significant increases in the real
price of oil.

“Higher priced energy may force policy-makers to think of
economic recession or slow growth as the usual state, and force
farmers to rethink agricultural inputs. The shift away from
high inputs to soil-conserving technology is theoretically
ideal from the perspective of moving to a sustainable agricultural
system. The downside, however, is that crops will be smaller
and food costs higher – probably much higher – than with industrial
agriculture,” she says.

The second
link, from economic change to the fertility rate, is based
on a theory called the “economic opportunity hypothesis” that
Abernethy first proposed more than 30 years ago. According
to her hypothesis, people increase the size of their families
when they are convinced that economic opportunities are expanding
and decrease family size objectives when they believe that
resources are shrinking and the difficulty of raising children
is increasing.

What is important in this regard is not how rich or poor a
society is, but the perception its people hold about how things
are changing. When the future appears threatening, for example,
people tend to exercise reproductive caution and adopt such
measures as marrying later and putting more space between births
within marriage. According to Abernethy, this correlation holds
true over the entire socioeconomic range and its predictions
differ substantially from the conventional view that increasing
educational levels in a society by itself can reduce fertility
rates.

Abernethy uses recent U.S. history to support her proposed
energy-fertility link.

Courtesy
of U.S. Department of Energy

Graph
showing increasing gap between U.S. energy consumption
and production

The
15-year burst in fertility rates that followed World War
II, known as the “baby boom,” was accompanied by the
widespread substitution of energy-intensive technology for
labor that substantially improved productivity. Higher productivity
and labor shortage in an expanding economy produced an increasingly
large and affluent middle class that “responded with early
marriage and closely spaced births.” The baby boom ended
within a year following rising energy prices and the 1961
recession.

Fertility rates fell to the lowest level ever recorded in
the United States following the oil-induced recession of
1980-81. Both white and black fertility rates plunged below
replacement level.

In the late 1980s, lower oil prices and other factors encouraged
rapid job growth. Nevertheless, the bottom half of wage-earners
enjoyed little increase in real income. So fertility rates
rose only slightly and the recession at the beginning of
1990 reversed the modest upward trend.

“The improving standard of living to which many societies
have become accustomed will be difficult to maintain in the
face of rapidly rising prices for energy. In these circumstances,
fertility rates are unlikely to rise. Indeed, a future marked
by declining energy use per capita may be the ultimate driver
of worldwide declines in fertility,” she writes.